• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.12
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• pp.777-784
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• 2016

All-vanadium redox flow batteries (VRFBs) are used as energy storage systems for multiple intermittent power sources. The performance of the VRFBs depends on the materials and operating conditions. Hence, performance characterization is of great importance in the development of the VRFBs. This paper proposes a method for determining the maximum current density based on stoichiometric ratios. A laboratory-scaled VRFB with a projected electrode area of $25cm^2$ is electrically charged when the state of the charge has begun from 0.6. The operating conditions, such as current density and volumetric flow rate are important in the test, and the maximum current density is influenced by the mass transfer coefficient. The results show that increasing the electrolyte flow rate from 5 mL/min to 60 mL/min enhances the maximum current density up to $520mA/cm^2$.

• Journal of the Korean Applied Science and Technology
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• v.34 no.2
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• pp.376-381
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• 2017

We were investigated by cyclic voltammetry to the stability through the electrochemical characteristics of Langmuir-Blodgett films mixed with myristic acid and stearic acid. Fatty acid mixture monolayer LB films was deposited by the LB method on the indium tin oxide(ITO) glass. The electrochemical properties was measured by cyclic voltammetry with a three-electrode system in 0.01 N $NaClO_4$ solution. The measuring range is continuously oxidized to 1650 mV, with an initial potential of -1350 mV was reduced. Scanning rates of 50, 100, 150, 200, and 250 mV/s was set. As a result, LB monolayer films of fatty acid mixture was appeared on irreversible processes by the oxidation current from the cyclic voltammogram. Diffusion coefficient (D) of fatty acid mixture was calculated $7.9{\times}10^{-2}cm^2s^{-1}$ at 0.01 N $NaClO_4$ solution.

• Journal of Radiation Protection and Research
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• v.31 no.2
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• pp.105-113
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• 2006

The oxidizing species are generated from the radiolysis of groundwater in the pore of buffer material around the canister used for the disposal of spent fuels. A mathematical model was introduced to calculate the cathodic current density induced by the oxidant around the canister, which determined the corrosion of carbon steel. An analytical solution was derived to get the cathodic current density in the cylindrical coordinate. The cathodic current densities from both the rectangular coordinate and cylindrical coordinate were compared with each other. The source terms and absorbed dose rate for the calculation of the radiolysis were calculated using the ORIGEN2 and MCNP computer code, respectively. The radius of the canister was determined with the new model in order to prevent the local corrosion. The results showed that the new solution made the cathodic current density around 25 % lower than the Marsh model.

• Journal of the Korean Vacuum Society
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• v.6 no.2
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• pp.103-108
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• 1997

Silicon field emitter arrays (FEAs) have been fabricated by a novel method employing a two-step tip etch and a spin-on-glass (SOG) etch-back process using double layered thermal/tetraethylortho-silicate (TEOS) oxides as a gate dielectric. A partial etching was performed by coating a low viscous photo resist and $O_2$ plasma ashing on order to form the double layered gate dielectric. A small gate aperture with low gate leakage current was obtained by the novel process. The hight and the end radius of the fabricated emitter was about 1.1 $\mu\textrm{m}$ and less than 100$\AA$, respectively. The anode emission current from a 256 tips array was turned-on at a gate voltage of 40 V. Also, the gate current was less than 0.1% of the anode current.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.373-378
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• 2021

The study aimed to develop a high-power enzymatic electrode for a wearable fuel cell that generates electricity utilizing lactate present in a sweat as fuel. Anode was fabricated by immobilizing lactate oxidase (LOx) on flexible carbon paper. As the lactate concentration in the electrolyte solution increased, the amount of current generated by catalysis of lactate oxidase increased. The immobilized LOx generated 1.5-times greater oxidation current density in the presence of gold nanoparticles than carbon paper only. Bilirubin oxidase (BOD)-immobilized cathode generated a larger amount of reduction current in the electrolyte saturated with oxygen than purged with nitrogen. A fuel cell composed of two electrodes was fabricated and cell voltage was measured under different discharge current. At the discharge current density of 66.7 ㎂/cm², the cell voltage was 0.5±0.0 V leading to maximum cell power density of 33.8±2.5 ㎼/cm².

• Electrical & Electronic Materials
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• v.5 no.4
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• pp.385-392
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• 1992

급속열산화방법으로 400-650.deg.C의 온도범위에서 10-600초 동안 n형 InP기판위에 InP자연산화막을 형성하고 산화막의 성장율, 성장기구와 화학적 구성성분 및 전기적 성질등을 조사하였다. InP자연산화막의 두께는 산화시간이 제곱근에 비례하였고 산화온도에 대하여 지수함수적으로 증가하였다. InP자연산화막은 320.deg.C의 온도에서 초기성장이 이루어지고 산소원자들이 InP내부로 확산되는 과정으로 형성되며 산화막 형성에 필요한 활성화에너지는 1.218eV이었다. InP 자연산화마그이 화학적성분은 In$_{2}$)$_{3}$, P$_{2}$O$_{5}$ 및 InPO$_{4}$의 산화물이 혼합하여 구성된다. Au/InP쇼트키다이오드와 InP자연산화막을 게이트절연물로 사용한 MOS 다이오드의 전기적 특성은 다이오드방정식에 따르는 전류-전압특성을 보였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.285-286
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• 2015

반도체 패키지 솔더범프용 주석계 도금액에 적용 가능한, 친환경 산화방지제 몇 종에 대하여 연구하였다. 주석계 전기도금액에 포함된 산화방지제는 주석의 산화방지 외에도, 전류효율, 도금액의 안정성, 그리고 형성된 솔더범프의 특성 등에 영향이 있음을 확인 하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.779-781
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• 2010

Trench D-MOS(double-diffusion MOS)는 기존의 D-MOS를 대체한 것으로 전체 전류의 길이를 짧게 함으로써 온전압강하가 낮아지게 된다. 따라서 소자가 턴-온시에 전력소모가 작게 되며, 온저항과 트레이드 오프관계인 턴-오프 특성도 그다지 나빠지지 않아 트레이드 오프 특성도 개선되어지는 장점이 있다. 본 논문은 MicoroTec 시뮬레이션을 이용하여 Trench D-MOS의 산화벽을 다르게하여 전류-전압 특성을 연구하였다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.2
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• pp.33-37
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• 2014

We have developed a novel passivation process employing a sacrificial gallium oxide process in order to recover the surface damage in AlGaN/GaN HFETs. Even with a conventional prepassivation process, surface damage during high temperature ohmic annealing cannot be avoided completely. Therefore, it is necessary to recover the damaged surface to avoid the characteristic degradation. In this work, a sacrificial gallium oxide process has been proposed in which the damaged surface after ohmic annealing was oxidized by oxygen plasma treatment and thereafter etched back using HCl. As a result, the leakage current was dramatically reduced and thus the subthreshold slope was significantly improved. In addition, the maximum drain current level was increased from 594 to 634 mA/mm. To verify the effects, the surface conditions were carefully investigated using X-ray photoelectron spectroscopy.

• Korean Journal of Materials Research
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• v.5 no.6
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• pp.633-638
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• 1995

Two types of $Ta_2O_{5}$, films, prepared by thermal oxidation and PECVD, on P-type(100) Si wafers were studied to examine the relationship between electrical properties and stresses of the films. For the thermally oxidized films, Ta films were depositied on the Si wafers by dc magnetron sputtering followed by thermal oxidation as functions of oxidation temperature and time. The PECVD films were deposited on the Si wafers as a fuction of RF power density. The relationship between the electrical properties and film stresses were studied. In the case of thermally oxidized $Ta_2O_{5}$ film, the electrical properties and film stress were not found to be dependent on each other, while PECVD $Ta_2O_{5}$ films showed that the electrical properties were depended on the film stress.